Nucleolar DNA Double-Strand Break Responses Underpinning rDNA Genomic Stability

DNA DSBs within rDNA arrays illicit a specialised nucleolar DNA damage response. Persistent rDNA DSBs result in Pol-I transcriptional inhibition and nucleolar reorganisation, resulting in the formation of nucleolar caps that contain rDNA arrays from individual nucleolar organiser regions (NORs). Accessibility of damaged rDNA in nucleolar caps promotes HDR. HDR occurs even in G1 cells and it has been argued that it can be templated in cis by...